Vasquez Rocks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Vasquez Rocks clear sky chart from 2005-11-05 to 2018-10-08.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
71%
17195
36%
50980
29%
17146
77%
17146
55%
23889

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
54%
780
29%
2680
26%
776
64%
776
37%
1343
January16th to endNight
52%
832
34%
2584
26%
832
64%
832
39%
1325
February1st to 15thNight
60%
760
34%
2287
28%
759
70%
759
45%
1171
February16th to endNight
58%
684
31%
2051
28%
684
66%
684
40%
1120
March1st to 15thNight
57%
780
27%
2340
23%
780
65%
780
44%
1206
March16th to endNight
67%
832
30%
2165
22%
832
72%
832
50%
1170
April1st to 15thNight
62%
779
32%
1949
18%
779
67%
779
52%
1073
April16th to endNight
67%
772
33%
1930
17%
772
72%
772
65%
954
May1st to 15thNight
71%
672
32%
1842
22%
672
74%
672
58%
898
May16th to endNight
71%
609
33%
1829
26%
609
73%
609
64%
789
June1st to 15thNight
84%
465
37%
1635
35%
465
88%
465
71%
578
June16th to endNight
96%
390
41%
1560
50%
390
96%
390
80%
457
July1st to 15thNight
92%
370
37%
1480
43%
370
92%
370
68%
479
July16th to endNight
90%
649
34%
1767
28%
609
91%
609
65%
791
August1st to 15thNight
93%
765
39%
1910
25%
761
93%
761
82%
847
August16th to endNight
95%
828
44%
2070
29%
828
95%
828
82%
926
September1st to 15thNight
92%
780
45%
1973
36%
780
92%
780
80%
886
September16th to endNight
90%
776
46%
2145
43%
776
93%
776
83%
862
October1st to 15thNight
77%
752
38%
2098
35%
752
82%
752
62%
983
October16th to endNight
73%
768
44%
2327
42%
768
80%
768
59%
1044
November1st to 15thNight
69%
760
35%
2470
32%
760
78%
760
55%
1082
November16th to endNight
67%
780
39%
2535
37%
780
75%
780
51%
1161
December1st to 15thNight
57%
780
34%
2535
27%
780
68%
780
40%
1273
December16th to endNight
52%
832
32%
2818
25%
832
65%
832
34%
1471

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
3212212235%71%
52138
Night
3312212235%69%
51177
TransparencyDay
16%26%15%28%29%
51830
Night
17%27%15%28%29%
50986
SeeingDay
411%30%35%13%5%
7330
Night
3315%35%33%8%
17202

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
7%323323346%59%
1585
16th to endDay
9%5%25%213335%58%
1989
February1st to 15thDay
5%413313246%62%
1901
16th to endDay
6%5%1442334458%
1709
March1st to 15thDay
5%31432345%7%58%
1950
16th to endDay
442432345%7%56%
2406
April1st to 15thDay
4423212236%64%
2329
16th to endDay
1212212247%71%
2305
May1st to 15thDay
2322212235%70%
2438
16th to endDay
2212212235%72%
2637
June1st to 15thDay
122111125%78%
2651
16th to endDay
111288%
2730
July1st to 15thDay
111221222378%
2730
16th to endDay
211111245%76%
2634
August1st to 15thDay
1112385%
2293
16th to endDay
11111485%
2484
September1st to 15thDay
1111111384%
2317
16th to endDay
1111112284%
2145
October1st to 15thDay
31221233472%
2028
16th to endDay
121221323375%
1896
November1st to 15thDay
231322233469%
1719
16th to endDay
332322335%7%62%
1755
December1st to 15thDay
341322445%8%59%
1755
16th to endDay
8%413423446%56%
1752
January1st to 15thNight
6%5%23323447%57%
2680
16th to endNight
6%5%24322246%59%
2584
February1st to 15thNight
45%23312346%62%
2281
16th to endNight
5%5%25%413435%57%
2051
March1st to 15thNight
4423315%45%8%57%
2340
16th to endNight
341232345%7%61%
2165
April1st to 15thNight
4423212336%65%
1949
16th to endNight
2212211345%72%
1930
May1st to 15thNight
412322246%68%
1842
16th to endNight
1312112235%74%
1828
June1st to 15thNight
1111136%80%
1635
16th to endNight
1111388%
1560
July1st to 15thNight
1121223379%
1560
16th to endNight
211213235%74%
1881
August1st to 15thNight
1111112384%
1920
16th to endNight
11122284%
2070
September1st to 15thNight
111112483%
1973
16th to endNight
1122386%
2145
October1st to 15thNight
131221333473%
2098
16th to endNight
231221212474%
2327
November1st to 15thNight
2312323245%68%
2470
16th to endNight
3312223347%65%
2535
December1st to 15thNight
4423324247%60%
2535
16th to endNight
6%5%24323346%57%
2818

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
25%37%16%27%20%
1585
16th to endDay
28%28%18%19%22%
1989
February1st to 15thDay
23%25%17%26%24%
1901
16th to endDay
29%27%17%31%12%
1709
March1st to 15thDay
23%410%21%20%18%
1950
16th to endDay
24%310%24%22%14%
2406
April1st to 15thDay
21%310%22%27%13%
2329
16th to endDay
13%410%21%33%16%
2305
May1st to 15thDay
15%310%19%30%20%
2438
16th to endDay
13%29%22%37%13%
2640
June1st to 15thDay
10%17%14%33%32%
2651
16th to endDay
5%126%27%56%
2730
July1st to 15thDay
11%149%22%51%
2581
16th to endDay
10%26%19%27%33%
2486
August1st to 15thDay
6%38%29%50%
2279
16th to endDay
6%138%37%43%
2484
September1st to 15thDay
7%15%9%29%47%
2317
16th to endDay
7%38%36%43%
2145
October1st to 15thDay
16%15%16%27%32%
2028
16th to endDay
14%25%12%25%39%
1896
November1st to 15thDay
19%25%17%31%23%
1719
16th to endDay
21%25%15%26%28%
1755
December1st to 15thDay
21%410%17%24%21%
1755
16th to endDay
29%37%19%23%15%
1752
January1st to 15thNight
25%37%17%26%20%
2680
16th to endNight
25%29%15%21%24%
2584
February1st to 15thNight
22%37%15%25%25%
2292
16th to endNight
28%37%16%29%14%
2051
March1st to 15thNight
23%410%19%23%18%
2340
16th to endNight
21%411%22%26%13%
2165
April1st to 15thNight
21%39%28%22%14%
1949
16th to endNight
11%310%24%32%17%
1930
May1st to 15thNight
15%49%21%31%18%
1843
16th to endNight
12%110%24%37%13%
1829
June1st to 15thNight
7%28%18%29%34%
1635
16th to endNight
5%37%26%57%
1560
July1st to 15thNight
8%1410%21%54%
1480
16th to endNight
12%26%15%26%36%
1767
August1st to 15thNight
6%127%29%53%
1910
16th to endNight
6%128%36%45%
2070
September1st to 15thNight
7%148%29%48%
1973
16th to endNight
5%129%38%42%
2145
October1st to 15thNight
15%15%14%32%30%
2098
16th to endNight
15%2211%25%41%
2327
November1st to 15thNight
17%17%15%29%27%
2470
16th to endNight
19%27%16%26%28%
2535
December1st to 15thNight
24%37%14%25%24%
2535
16th to endNight
27%48%16%25%17%
2818

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
10%22%30%31%4
123
16th to endDay
10%19%35%22%9%1
331
February1st to 15thDay
6%18%30%28%11%2
326
16th to endDay
9%24%30%26%8%
290
March1st to 15thDay
10%20%33%23%11%
330
16th to endDay
8%16%37%26%9%
352
April1st to 15thDay
10%17%37%22%10%1
329
16th to endDay
425%35%22%8%3
318
May1st to 15thDay
215%38%28%10%4
348
16th to endDay
411%37%32%9%3
394
June1st to 15thDay
8%30%37%14%9%
375
16th to endDay
1327%38%17%11%
375
July1st to 15thDay
1119%46%20%11%
365
16th to endDay
216%48%19%13%
391
August1st to 15thDay
126%47%13%10%
359
16th to endDay
20%49%17%11%
396
September1st to 15thDay
329%46%16%3
375
16th to endDay
6%30%41%18%3
375
October1st to 15thDay
13%37%35%11%1
345
16th to endDay
29%29%34%22%
312
November1st to 15thDay
5%8%24%31%21%8%
135
16th to endDay
5%10%30%35%16%1
135
December1st to 15thDay
5%12%25%40%14%1
135
16th to endDay
7%18%25%31%13%3
116
January1st to 15thNight
7%7%21%41%17%4
780
16th to endNight
9%8%23%36%19%2
832
February1st to 15thNight
5%422%38%23%5%
764
16th to endNight
7%7%22%37%21%4
684
March1st to 15thNight
46%26%36%21%4
780
16th to endNight
35%17%41%26%4
832
April1st to 15thNight
36%21%38%25%3
779
16th to endNight
25%22%36%26%6%
772
May1st to 15thNight
1418%40%31%4
673
16th to endNight
1418%38%32%4
611
June1st to 15thNight
110%36%45%5%
465
16th to endNight
135%55%7%
390
July1st to 15thNight
119%68%10%
370
16th to endNight
1220%60%15%
649
August1st to 15thNight
1124%56%16%
765
16th to endNight
119%57%20%
828
September1st to 15thNight
1226%50%19%
780
16th to endNight
7%34%43%13%
776
October1st to 15thNight
2311%45%30%6%
752
16th to endNight
2217%33%31%11%
768
November1st to 15thNight
2218%41%28%6%
760
16th to endNight
3320%37%28%6%
780
December1st to 15thNight
6%7%20%40%22%3
780
16th to endNight
8%9%22%37%17%3
832
Page generated at 2018-10-09 07:39:14. Version ac04

Copyright 2018 A. Danko


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